1. Field of the Invention
The present invention relates to systems and methods for communicating with a drill string and more particularly to systems and methods for communicating with a drill string data network when a drill string is not actively drilling.
2. Background
The oil drilling industry has long sought to retrieve downhole information more reliably and at faster rates while drilling. For example, U.S. Pat. No. 6,670,880, issued to Hall et al., discloses a downhole transmission system that transmits data by way of a transmission system integrated into a drill string. This transmission system utilizes data transmission couplers installed in the ends of downhole tools to transmit data across the tool joints. Data is transmitted to the data transmission couplers by way of a cable or other transmission line routed through each downhole tool.
During drilling, a rotary connector may be used to enable communication between the Hall transmission system and surface equipment. In certain cases, the rotary connector may be used in place of a saver sub. Like a saver sub, the rotary connector is inserted between the threaded portion of the top drive or kelly and the drill string and may save the threads of the top drive or kelly from excessive wear. During tripping or other operations, the rotary connector is typically disconnected from the drill string, which severs communication between surface equipment and the drill string. Thus, data cannot be uploaded to or downloaded from the drill string during this time period.
In general, the term “tripping” refers to a set of operations performed to remove and/or replace an entire drill string or a portion thereof from a borehole. For example, tripping is necessary for a number of well operations that change the configuration of a bottom-hole assembly, such as replacing a bit or another tool, adding a mud motor, or adding measurement while drilling (MWD) or logging while drilling (LWD) tools, reaching the casing point, or running a wireline tool. Tripping can take many hours if downhole tools are to be brought to the surface, depending on the depth to which drilling has progressed.
The ability to maintain communication with downhole tools and instruments during tripping can enable a wide variety of MWD and LWD measurements to be taken during time that might otherwise be wasted. This ability can also enhance safety. For example, in the event that a pocket of high-pressure gas breaks through into a well bore, the crew can be given critical advance warning of a dangerous “kick,” and timely action can be taken to protect the crew and save the well. Maintaining communication during tripping can also give timely warning of lost circulation or other potential problems, enabling timely corrective action, which can save time and money.
In view of the foregoing, what is needed is a system and method for communicating with a drill string during tripping or other periods of drilling inactivity. Such a system and method would ideally maintain communication between a drill string and surface equipment even when a direct connection with the drill string transmission system is broken or interrupted. Furthermore, such a system and method would ideally be simple and not interfere with rig floor activities, tripping or other activities around or near the drill string.